During many manufacturing operations, it is necessary that single sheets of material be removed from a stack of such sheets for subsequent processing or manufacturing operations. Such sequential unstacking or destacking of the sheets is frequently necessary during operations involving floor tiles, steel sheets, mirrored or ceramic tiles, cardboard or plastic sheets, and the like. For example, it is typically necessary during the manufacture of floor tile to remove partially finished tiles one at a time from a stack for subsequent application of adhesive backing, high-gloss plastic coating, or like finishing materials.
While it is usually desirable to provide a system which destacks sheets of material as quickly as possible, a major concern is avoiding scratching, marring, or other damage to the sheets, either by contact with each other or with the handling apparatus. This latter concern is particularly important in the destacking of materials such as floor or ceramic tiles since one surface of the sheet is generally exposed to view, and damage to that surface can prevent the tile from meeting the required standard of quality. Similarly, mirrored tiles require careful handling to avoid damage to their silvered surfaces.
Various arrangements have previously been employed for performing the destacking function. For example, some apparatus include roller or reciprocating plate mechanisms for sliding either the uppermost or lowermost sheet of material from the stack. As will be appreciated, however, such devices may result in high rates of rejection since the sliding contact of one sheet against another frequently damages the sheets. Other arrangements have employed movable suction devices such as for picking up the top sheet of a stack and moving it therefrom. However, these arrangements are frequently overly complex in design, and can be undesirably slow in their operation. Still other arrangements, such as for destacking of ferrous sheets of material, have employed magnetic devices for removing sheets from a stack. Obviously, such arrangements are completely unsuitable for use with non-ferrous materials, and are typically incapable of operating at desirably high speed.
In view of the shortcomings of heretofore known arrangements for destacking or unstacking sheets of material from a stack, it is desirable to provide an apparatus for destacking sheets of material which is operable at relatively high rates of speed, and which minimizes problems of marring or other damage to the sheets as they are handled. It is particularly desirable that such an apparatus be readily adaptable for handling sheets of various thicknesses, as well as for handling sheets of different materials, including vinyl and other plastics, wood, metal, glass, ceramics and cardboard.